Electrical apparatus



Aug. 4, 1942.

Filed July 20, 1940 2 Sheets-Sheet 1 WITNESSES: INVENTOR f I James '7, Nercrzau W4. 6 Maw ATTORNEY Aug- 4, 1 4 J. T. MERCEREAU ELECTRICAL APPARATUS 2 Sheets-Sheet 2 INVENTOR James 7: lfercerea 1/.

BY M Filed July 20, 1940 WITNESSES: j/XLM'V.

ATTORNEY Patented Aug. 4, 1942 ELECTRICAL APPARATUS James T. Mercereau, Sharon, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application July 20, 1940, Serial No. 346,566

Claims.

My invention relates to electrical apparatus and particularly to such apparatus in which a motor is operated in the one or the other direction to change a condition of the apparatus, such as in the application of a motor operated tap-changing mechanism to transformers for changing the voltage ratio between the primary and secondary circuits connected to the transformer.

In such apparatus, it is customary to provide motor limit switches operable by some part of the apparatus when it is actuated to given limiting positions in the one or the other direction of travel within an operative range to automatically interrupt the operation of the motor and prevent further operation of the apparatus in a given direction until the apparatus has again been operated in the other direction, to thus limit the operation of the apparatus within a desired range. It sometimes happens that, for one reason or another, the limit switches fail to operate to stop the motor at the desired limit of the range of operation of the apparatus. I have provided a mechanism including a clutch that is effective in such circumstances to disconnect the apparatus from the motor to thus permit continued operation of the motor without causing further operation of the apparatus beyond given limits.

It is an object of my invention to provide, in apparatus of the character described, a clutch mechanism operative upon operation of the apparatus to a given limit of its intended range of operation in the one or the other direction for disconnecting the apparatus from the motor.

It is a further object of my invention to provide a clutch mechanism of the character described in which timing means is provided for releasing the clutch at both ends of the normal travel of the apparatus by means of a single mechanical release.

Other objects and advantages of the invention will be apparent from the following description of a preferred embodiment of the invention, ref erence being had to the accompanying drawings, in which:

Figure 1' is a diagrammatic view of apparatus embodying the invention;

Fig. 2 is an elevational view, partly in section, taken along the line II-II of Fig. 3;

Fig. 3 is a vertical sectional view of the clutch and operating mechanism therefor; and

Fig. 4 is a vertical sectional view of a portion of the apparatus shown in Fig. 3 with parts in other operative positions.

Referring to Fig. 1, supply circuit conductors I and 2 are illustrated connected to a transformer winding 3 through which electrical energy is sup plied to the load circuit conductors 42, the winding 3 being provided with tapped conductors 5 that are adapted to be connected through a tap changing switch 6 to the secondary conductor 4 in accordance with the selected position of the tap changing switch, as determined by the tapchanging operating mechanism. This mechanism includes a switch operating shaft '1 driven through mechanical gearing 8 by a shaft 9 and the clutch mechanism shown generally at H through a gear wheel l2 and pinion l3 driven by a motor 14 in the one or the other direction, as controlled by a primary voltage relay 15 that is energized through a transformer It in accordance with the voltage between secondary circuit conductors 42 in a well known manner.

Referring particularly to Fig. 3, the gear wheel 12 is positioned about a bearing 2| in a portion of the frame structure 22 within which is provided abearing 23 for the shaft 9 through which the tap changing mechanism is operated. A collar 24 is provided and attached by means of screw bolts 25 to the end of the frame member 22 to retain the bearings 23 in place and about this collar one ring portion 26 of a clutch member is positioned and attached by means of screw bolts 21 to the gear wheel 12, the member 26 having teeth 28 extending outwardly therefrom to engage similar teeth provided on a sleeve member 29 comprising the other cooperative element of the engaging clutch members. The member 29 is shown in its operative position in which the clutch teeth are in engagement. An inwardly extending flange 31 is provided which, in the illustrated position of the member 29, is in engagement with a movement limiting stop 32 that is attached to the shaft 9 by pin 33. The flange 3| provides an abutment at one end of a chamber 34 within the sleeve 29 for accommodating a spring 35 one end of which engages the flange 3| and the other end of which engages a collar 36 that is attached by means of screw threads 31 to the end of the shaft 9. Key members 38 are provided extending into recesses provided in the shaft 9 and in the collar 36 for locking the collar on the shaft so that the collar and shaft turn as a unitary structure. Driving members 42 are provided on the sleeve 29 and extend through slots 43 (see Fig. 2) provided in the collar 36. A flange 44 extends outwardly from the end of the sleeve 29 providing an annular recess 45 in which the bifurcated end of a clutch release lever 45 is positioned carrying contact buttons 41 thereon for engaging the inner surface of the flange 44. The lower end of the lever 46 is pivoted by pins 49 to a portion of the frame structure 5| upon which the operating mechanism for the lever 45 is mounted. This operating mechanism includes a shaft 52 having a screw threaded outer portion for engaging light threads on a cooperating traveling nut 53 having a lower portion 54 that extends between guide members 55 on the frame portion between which the extension 54 is permitted to slide but which prevents rotation of the nut 53 on the shaft 52.

One end 56 of the shaft 52 is round and positioned in a recess in a bushing 57 to form a bearing therein, which bushing is mounted in a portion of the frame 58 and forms an abutment against which a shoulder 59 of the shaft 52 is adapted to engage. The opposite end SI of the shaft 52 is likewise rounded and mounted within a bushing 62 positioned within a portion of the frame structure 53 to form a bearing for the other end of the shaft 52. A shoulder 64 is likewise provided on the opposite end of the threaded portion of the shaft 52 from the shoulder 59 for engaging a movable abutment shown as a washer 65 positioned about the shaft 52 and adapted to engage contact buttons 56 carried by the lever 46.

As best shown in Fig. 2, a portion of the shaft 52 is a square cross section about which a hub 51 of a gear wheel 58 is positioned that meshes with a pinion 59 mounted on a bearing ii on the frame structure 63 and operatively connected through a square portion 72 of the shaft 9.

During normal operation of the tap changing mechanism, as controlled by the motor l4 and the primary relay I5, the gear wheel [2, driven by the motor, drives the shaft 9 of the tap changing mechanism through the engaging teeth 29 on the collar 25 and the sleeve 29 of the clutch members which are in the position illustrated in Fig, 3, in which the spring 35 maintains the sleeve 29 in clutch engaging position so that the rotation of the wheel i2 is communicated to the sleeve 29 through the teeth 28 and through the driving members 42 at the other end of the sleeve 29 to the collar 36 keyed to the shaft 9.

As the shaft 9 rotates, the pinion 69 on the end thereof similarly rotates to drive the gear wheel 68 and the screw threaded shaft 52, causing the nut 53 to travel along the shaft in the one or the other direction in accordance with the direction of operation of the tap changing mechanism. During the operation of the tap changing mechanism within its operative range, the nut 53 travels from one extreme position shown in Fig. 3 to the opposite extreme position shown in Fig. 4. If the mechanism is operating in a direction such that the nut 53 is traveling toward the right as shown in Figs. 3 and l, and has reached the position shown in Fig. 3, and if the limit switches controlling the operation of the motor fail to stop the motor at this limiting position, further movement of the nut 53 toward the right after engagement with the movable abutment 65 causes this abutment to be moved away from the shoul ders 64 on the shaft 52 to effect pressure against the buttons 55 carried by the lever 46, moving the lever in a clockwise direction about the pivot pin 49 and causing the pressure buttons 4"! at the upper end of the lever to press against the inner side of the flange 44 to move the sleeve 29 toward the right, the extension portions 42 sliding in the notches 43 in the collar 36. This motion will continue until the sleeve 29 is moved toward the right a sufiicient distance that the clutch teeth 28 on the sleeve 29 are disengaged with the teeth on the collar 26 so that continued rotation of the gear wheel I2 does not cause the sleeve 29 and the shaft 9 to continue further rotation. Consequently, further movement of the shaft 52 and of the clutch release lever 46 is discontinued. After the clutch has been operated to its release position, the equipment is again placed in condition for automatic operation by manual operation of the shaft 9 a sufficient number of turns to cause the clutch release lever 46 to be moved in a counter-clockwise direction, or to the position shown in Fig. 3, to again permit engagement of the clutch teeth 28 under pressure of the spring 35.

If the mechanism is operating in a direction corresponding to the travel of the nut 53 toward the left, as viewed in Figs. 3 and 4, and has reached the desired limit of travel of the apparatus so that the nut 53 is in engagement with the bushing 57 (Fig. 4) further operation of the shaft 52 in the same rotative direction causes it to be moved toward the right, the end portions 56 and 5| of the shaft 52 sliding in the bushings 51 and 62, respectively, and the shoulder 64 on the shaft 52 forcing the movable abutment or washer 65 toward the right against the pressure buttons 55 to again move the clutch release lever 46 in a clockwise direction about the pivot 49 to release the clutch in the same manner as above described.

It will be appreciated that in this direction of operation of the mechanism, since the nut 53, in traveling toward the left cannot travel further in this direction after engaging with the bushing 51, a further rotation of the shaft 52 will cause it to move toward the right and effect the above described lever 45.

It will be appreciated, therefore, that in either direction of operation of the shaft 52, when the nut 53 has moved in the one direction or the other direction, a sufiicient amount to engage the one or the other of the abutments 51 or 65, the total length of the members 52 and 53 between these abutments expands, forcing them apart so as to effect a similar operation of the clutch mechanism at either limit of travel of the mecha nism. The clutch, therefore, makes it impossible to damage the equipment by accidental overtravel of the operating motor. The limits of travel at which it is desired that the clutch shall be operated may be adjusted by adjusting the position of the bushing 51 within the frame member 58 to vary the distance between this bushing and the abutment 65. A locking mechanism 13 is provided for maintaining the bushing 5'! in its adjusted position.

Modifications in the apparatus illustrated and described will occur to those skilled in the art within the spirit of my invention, and I do not wish to be limited otherwise than by the scope of the appended claims.

I claim as my invention:

1 In combination, a, driven mechanism having a given range of operation, motor-operated driving means for operating the mechanism, clutch means for operatively connecting the driving means to the driven mechanism, a clutch operating member for actuating the clutch means to disconnect the driving means from the driven mechanism, means for actuating the clutch operatmg mechanism comprising cooperating screw threaded shaft and nut members, and means for rotating one of said members in accordance with the operation of the driven mechanism to cause relative movement of the two members throughout the given range of operation of the driven mechanism such that an expanding total length of said two members occurs upon further movement after the mechanism has reached the limit of its range of operation in either direction.

2. In combination, a driven mechanism having a given range of operation, motor-operated driving means for operating the mechanism, clutch means for operatively connecting the driving means to the driven mechanism, a clutch operating member for actuating the clutch means to disconnect the driving means from the driven mechanism, means for actuating the clutch operating mechanism, comprising a fixed abutment and a movable abutment and cooperating screw threaded shaft and nut members positioned between said abutments, means for rotating one of said members in accordance with operation of the driven member to cause relative movement of the two members, the screw and nut members being so arranged that one overtravels the other to effect an expanding total length of said two members upon further movement after a predetermined operation of the mechanism in either direction.

3. In combination, a driven mechanism having a given range of operation, motor-operated driving means for operating the mechanism, clutch means for operatively connecting the driving means to the driven mechanism, a clutch operating member for actuating the clutch means to disconnect the driving means from the driven mechanism, means for actuating the clutch operating mechanism comprising a fixed abutment and a movable abutment and cooperating screw threaded shaft and nut members positioned between said abutments, means for rotating the shaft in accordance with the operation of the mechanism, means for holding the nut against rotation while permitting travel along the shaft member, the screw and nut members being so arranged that the nut engages the one or the other of said abutments after a predetermined operation of the mechanism in either direction to effect movement of the movable abutment upon continued operation thereof in the same direction.

4. In combination, a driven mechanism having a given range of operation, motor-operated driving means for operating the mechanism, clutch means for operatively connecting the driving means to the driven mechanism, a clutch operating member for actuating the clutch means to disconnect the driving means from the driven mechanism, means for actuating the clutch operating mechanism comprising a pair of cooperating gear members, and means for actuating one of said members in accordance with the operation of the driven mechanism to cause relative movement of the two members throughout the given range of operation of the driven mechanism with out operating said clutch operating member and effective upon further relative movement of said two members upon further movement after the mechanism in either direction to operate the clutch operating member to disconnect the driving means from the driven mechanism.

5. In combination, a driven mechanism having a given range of operation, motor-operated driving means for operating the mechanism, clutch means for operatively connecting the driving means to the driven mechanism, a clutch operating member for actuating the clutch means to disconnect the driving means from the driven mechanism, means for actuating the clutch operating mechanism comprising a fixed abutment and a movable abutment and cooperating screw threaded shaft and nut members positioned between said abutments, means for rotating one of said members in accordance with operation of the driven member to cause relative movement of the two members, the screw and nut members being so arranged that, after a predetermined travel of one member with respect to the other, further travel in either direction efiects an expanding total length of said two members between said abutments for actuating the clutch operating mechanism.

JAMES T. MERCEREAU. 

